1. Field of the Invention
This invention pertains generally to an apparatus and method to locate and mark the location of an underground utility, and more particularly to an apparatus and method to locate and mark the location of an underground utility on pavement or on ground from a vehicle while in motion.
2. Description of Related Art
Conventional practice for locating an underground utility usually involves a manual technique where a technician carries a handheld sensor with audio feedback to determine the surface location of a particular utility. The technician then marks the location of the utility on the ground with aerosol paint, a flag or both. A specific color paint or flag usually denotes a specific utility. Often the technician writes graffiti-like with paint on the ground or pavement to denote the specific utility. The technician then walks along the general direction of the underground utility for a reasonable distance and repeats the locating and marking process. This manual locating and marking routine requires a knowledgeable operator who can interpret the positional audio signal of a utility detector and is physically capable of walking the utility route and applying aerosol paint and/or flags to the ground. For underground utilities that must be marked for an extended distance, such as along a road or right-of-way, this routine becomes laborious and time-consuming. The technician may also be exposed to moving traffic and other hazards during the routine. The manual locating and marking process is further hindered when adverse terrain and weather conditions are present.
More recent utility locating equipment may use ground penetrating radar, Radio Frequency (RF) marker systems or other electronic locator equipment to determine the utility location and then input the surface location into a Geographic Information System (GIS) using a positional location system such as a Global Positional System or GPS. If any excavation is contemplated, however, the technician would use the GIS information and a GPS receiver to locate the general area of the utility, and then use a hand held sensor to confirm the position on the ground and manually apply the paint or the flags.
There have been several devices designed to improve the manual utility marking process. For example, U.S. Pat. No. 5,918,565 teaches a flag carrier and paint application device that is carried by the technician to make it easier to apply paint or flags as markers. The technician must first locate the utility with a detector and then apply the markers by hand. U.S. Pat. No. 4,738,060 teaches a permanent spike and marker for locating an underground utility over ground. The technician must first locate the utility and then apply the spike marker by hand. Other hand deployed utility markers include those described in U.S. Pat. No. 5,056,454, U.S. Pat. No. 5,568,785 and U.S. Pat. No. 6,095,081. All of these devices require the technician to locate and mark the utility manually.
There are also a number of methods and detectors used to locate underground utilities. For example, U.S. Patent Application No. 2002/0130806 A1 teaches a method for detecting, mapping and locating underground utilities. It does not, however, teach any marking system. U.S. Pat. No. 6,462,696 teaches a man-portable radar system for locating underground utilities. This patent does not teach marking the utility position once it is located. U.S. Pat. No. 6,437,572 teaches a method and apparatus for locating utilities using an interactive RF system. This patent does not teach marking the utility position once it is located. U.S. Pat. No. 6,195,992 teaches a geologic data acquisition system that characterizes the subsurface geology for efficient operation of an excavator. It can also locate underground utilities. This patent discloses a vehicle-towed system to collect and process the subsurface data and the ability to adapt to a plurality of underground locator systems. The patent does not teach any surface marking device or method.
Another class of detection and marking devices are designed to discover and mark buried hazards such as radioactive deposits or land mines. These devices, however, are not for use with continuous linear underground utility systems. For example, U.S. Pat. No. 5,025,150 discloses a survey vehicle that detects radioactive sources in the ground and marks their location with a spot of paint. The apparatus described in that patent uses multiple detectors to locate individual radioactive sources in a target area and a paint applicator for each detector to mark the surface with a spot of paint. This device does not teach detecting or marking the position or path of an underground utility. U.S. Pat. No. 6,026,135 discloses a multi-sensor, vehicle-mounted land mine detector. This device is designed to detect and confirm a land mine location and then temporarily mark the location with a semi-solid gel. The device remains motionless while confirming and marking the location. This patent does not teach detecting or marking a linear underground utility system.
Other detection and marking devices are used to repaint traffic lines on roads and highways. For example, U.S. Pat. No. 5,169,262 discloses a traffic line repainting apparatus that attaches to a vehicle, optically detects old paint, and applies new paint to the same location. That device depends on an optical sensor to detect old paint. The patent does not teach applying a new mark, a unique mark or marking a non pavement surface. U.S. Pat. No. 5,203,923 shows a traffic line repainting apparatus that uses a paint detector and a paint applicator. That device repaints based on optical detection of previous paint on pavement and does not teach underground utility detection, unique symbol marking or use on a non-pavement surface.
Accordingly, there is a need for an apparatus and method that automates locating and marking underground utilities. The present invention satisfies those needs, as well as others, and overcomes deficiencies inherent in previously developed devices and methods for locating and marking underground utilities.